Cold Ac when Idle and Hot when driving? Any Ideas

08 7.3 F-350 at Idle A/C blows cold air. Start driving and A/C begins to blow warm air. HELP Idle ac cold ,driving crusing warm air.
We have checked amount of freon, check for restriction in orifice tube, cleaned all heat exchangers, and now we re just frustrated because this is just backwards for a normal airflow problem. Has anyone seen this before? The truck is equipped with a big bumper and we thought at first it may be causing the problem

Check your AC clutch engagement, the clutch may be worn enough that it will not hold lockup at higher RPM's. I went through the same problem with my 99, cold when idle & low speed & started blowing hot on highway. AC clutch was worn enough that it couldn't hold when driving. Removed a shim & it works perfect now.
I got the info on the exact procedure for measuring spacing of clutch on a web search, don't remember the site but I can look for it later if y'all don't have luck locating it.

I do remember to test it, all you had to do was drive with AC on & when it started blowing hot, pull over, pop hood & see if clutch is engaged. If not, tap it with a solid object & if it engages, bingo.... you know what's wrong. Just be careful tapping the clutch when the engine is running, don't drop your tappy tool lol

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